CODEWITHSUNDEEP
c++winapiunicode
user593747
user593747

Reputation: 1514

Convert a 'const wchar_t *' to 'unsigned char *'

In C++ is it possible to convert a 'const wchar_t *' to 'unsigned char *'?

How can I do that?

wstring dirName;
unsigned char* dirNameA = (unsigned char*)dirName.c_str();

// I am creating a hash from a string
hmac_sha256_init( hash, (unsigned char*)dirName.c_str(), (dirName.length)+1 );

Upvotes: 4

Views: 6638

Answers (3)

user2058002
user2058002

Reputation:

Since you're using WinAPI, use WideCharToMultiByte.

Upvotes: 2

Larry Osterman
Larry Osterman

Reputation: 16142

Try using reinterpret_cast. So:

unsigned char * dirNameA = reinterpret_cast<unsigned char *>(dirName.c_str());

That might not work because c_str returns a const wchar_t *so you can also try:

unsigned char * dirNameA = reinterpret_cast<unsigned char *>(
                               const_cast<wchar_t *>(dirName.c_str())
                           );

This works because hmac_sha256_init should accept a binary blob as its input, so the unicode string contained in dirName is an acceptable hash input.

But there's a bug in your code - the length returned by dirName.length() is a count of characters, not a count of bytes. That means that passing too few bytes to hmac_sha256_init since you're passing in a unicode string as a binary blob, so you need to multiply (dirName.length()) by 2.

Upvotes: 2

Foo Bah
Foo Bah

Reputation: 26251

You need to convert character by character. There are functions like wcstombs to do this.

Upvotes: 2

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